* {
    box-sizing: border-box;
}
​
body {
    margin: 0;
}
.column {
    float: left;
    width: 33.33%;
}


.row:after {
    content: "";
    display: table;
    clear: both;
}


@media screen and (max-width: 600px) {
    .column {
        width: 100%;
    }
}